Python HMAC Code Example (Online Runner)

Python HMAC examples with selectable hash algorithms, input encodings, and hex/Base64 output to match the online tool.

Online calculator: use the site HMAC tool.

Calculation method

The online tool lets you choose the hash algorithm, message encoding, key encoding, and output encoding. The helper below mirrors those options using Python’s hmac and hashlib modules.

Note: RIPEMD-160 depends on your OpenSSL build; if it is missing, install pycryptodome and use Crypto.Hash.RIPEMD160.

Implementation notes

Package: built-in hmac and hashlib (plus optional pycryptodome for RIPEMD-160).
Implementation: the helper normalizes message/key encodings and supports hex/base64 output to match the UI.
Notes: HMAC is a keyed MAC, not a hash; always keep the key secret. Use hmac.compare_digest for timing-safe comparisons when verifying tags.

import base64
import hashlib
import hmac
from typing import Literal

Algorithm = Literal[
    "sha1",
    "sha224",
    "sha256",
    "sha384",
    "sha512",
    "sha3-256",
    "sha3-512",
    "ripemd160",
    "md5",
]
Encoding = Literal["utf8", "hex", "base64"]
OutputEncoding = Literal["hex", "base64"]


def _decode(value: str, encoding: Encoding) -> bytes:
    if encoding == "hex":
        return bytes.fromhex(value)
    if encoding == "base64":
        return base64.b64decode(value)
    return value.encode("utf-8")


def _encode(value: bytes, encoding: OutputEncoding) -> str:
    return base64.b64encode(value).decode("ascii") if encoding == "base64" else value.hex()


def _digestmod(algorithm: Algorithm):
    if algorithm == "sha3-256":
        return hashlib.sha3_256
    if algorithm == "sha3-512":
        return hashlib.sha3_512
    if algorithm == "ripemd160":
        return lambda data=b"": hashlib.new("ripemd160", data)
    return getattr(hashlib, algorithm)


def hmac_digest(
    message: str,
    key: str,
    algorithm: Algorithm = "sha256",
    message_encoding: Encoding = "utf8",
    key_encoding: Encoding = "utf8",
    output_encoding: OutputEncoding = "hex",
) -> str:
    msg_bytes = _decode(message, message_encoding)
    key_bytes = _decode(key, key_encoding)
    mac = hmac.new(key_bytes, msg_bytes, _digestmod(algorithm))
    return _encode(mac.digest(), output_encoding)

# Example usage
message = "hello"
key = "secret"

print(hmac_digest(message, key, algorithm="sha256"))
print(hmac_digest("68656c6c6f", key, algorithm="sha256", message_encoding="hex"))
print(hmac_digest(message, "c2VjcmV0", algorithm="sha256", key_encoding="base64", output_encoding="base64"))

File HMAC example

from pathlib import Path
from typing import Literal
import hashlib
import hmac
import tempfile

Algorithm = Literal[
    "sha1",
    "sha224",
    "sha256",
    "sha384",
    "sha512",
    "sha3-256",
    "sha3-512",
    "ripemd160",
    "md5",
]


def _digestmod(algorithm: Algorithm):
    if algorithm == "sha3-256":
        return hashlib.sha3_256
    if algorithm == "sha3-512":
        return hashlib.sha3_512
    if algorithm == "ripemd160":
        return lambda data=b"": hashlib.new("ripemd160", data)
    return getattr(hashlib, algorithm)


def hmac_file(path: Path, key: str, algorithm: Algorithm = "sha256") -> str:
    hasher = hmac.new(key.encode("utf-8"), digestmod=_digestmod(algorithm))
    with path.open("rb") as handle:
        for chunk in iter(lambda: handle.read(1024 * 1024), b""):
            hasher.update(chunk)
    return hasher.hexdigest()

with tempfile.TemporaryDirectory() as temp_dir:
    sample_path = Path(temp_dir) / "sample.bin"
    sample_path.write_bytes(b"hello")
    print(hmac_file(sample_path, key="secret", algorithm="sha256"))

Complete script (implementation + tests)

import hashlib
import hmac


def run_tests() -> None:
    expected = "88aab3ede8d3adf94d26ab90d3bafd4a2083070c3bcce9c014ee04a443847c0b"
    actual = hmac.new(b"secret", b"hello", hashlib.sha256).hexdigest()
    assert actual == expected, "HMAC-SHA256 mismatch"
    print("All HMAC tests passed.")


if __name__ == "__main__":
    run_tests()